Microwave transmission lines are well known and often take the form of a flexible or semi-rigid coaxial cable. U.S. Pat. Nos. 4,16I,704 and 4,486,726 disclose modules with circuit components disposed therein, which are disposed along coaxial cables. As noted in the '704 patent, a typical outer diameter range of the coaxial cable is 0.034-0.250 inches. If the transverse dimensions of the circuit component within the module greatly exceed the outer diameter of the coaxial cable, the component cannot be integrated into the cable.
It has been conventional to provide a threaded connector between one end of the cable and one end of such components. Threaded connectors on components such as attenuators can have transverse dimensions greater than those of the attenuator itself. Threaded connectors increase the length and weight of the microwave component and constitute areas for potential losses.
It is also known that there are several important requirements that an interface between a coaxial cable and circuit component must satisfy. The connector or connectorless joint must present a constant characteristic impedance, must have controlled compensation of electrical discontinuities resulting from unavoidable dimensional changes, must meet close mechanical dimensional tolerances, and must not introduce reflections in the microwave transmission line.
Further, it is often important that microwave components be placed within a hermetically sealed module, so that the sensitive electronic components will not be damaged in a non-hermetic environment. A typical standard for the effectiveness of a hermetic seal is defined in MIL-STD-883, Method 1014.5.
Electronic components disposed in modules along microwave transmission lines may also be subject to mechanical stresses. It is therefore preferable that the conductive members disposed between the coaxial cable and the electronic components in the module be "captivated" so that stresses on the coaxial cable will not be transmitted to and affect the mechanical integrity of the module or the electronic components in it.
It is an object of the present invention to provide a connectorless joint between a coaxial cable and a module containing microwave components which meets the requirements for mechanical strength, dimensional tolerances, and constant characteristic impedance for such joints.
Another object of the invention is to eliminate a space constraint in densely populated systems by providing a means of integrating active and passive electronic components into the same space occupied by a cable assembly.
It is another object of the invention to provide a means of adding a component into the space occupied by an existing cable assembly in a configured system when modification or upgrade is required.
It is another object of this invention to provide a hermetically sealed housing integrated in a coaxial cable assembly for the purpose of providing hermetic protection to sensitive electronic components.